summaryrefslogtreecommitdiffstats
path: root/doh.cc
blob: 1c8610255f25dae004cc613353cfd81fe107bb6e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
1094
1095
1096
1097
1098
1099
1100
1101
1102
1103
1104
1105
1106
1107
1108
1109
1110
1111
1112
1113
1114
1115
1116
1117
1118
1119
1120
1121
1122
1123
1124
1125
1126
1127
1128
1129
1130
1131
1132
1133
1134
1135
1136
1137
1138
1139
1140
1141
1142
1143
1144
1145
1146
1147
1148
1149
1150
1151
1152
1153
1154
1155
1156
1157
1158
1159
1160
1161
1162
1163
1164
1165
1166
1167
1168
1169
1170
1171
1172
1173
1174
1175
1176
1177
1178
1179
1180
1181
1182
1183
1184
1185
1186
1187
1188
1189
1190
1191
1192
1193
1194
1195
1196
1197
1198
1199
1200
1201
1202
1203
1204
1205
1206
1207
1208
1209
1210
1211
1212
1213
1214
1215
1216
1217
1218
1219
1220
1221
1222
1223
1224
1225
1226
1227
1228
1229
1230
1231
1232
1233
1234
1235
1236
1237
1238
1239
1240
1241
1242
1243
1244
1245
1246
1247
1248
1249
1250
1251
1252
1253
1254
1255
1256
1257
1258
1259
1260
1261
1262
1263
1264
1265
1266
1267
1268
1269
1270
1271
1272
1273
1274
1275
1276
1277
1278
1279
1280
1281
1282
1283
1284
1285
1286
1287
1288
1289
1290
1291
1292
1293
1294
1295
1296
1297
1298
1299
1300
1301
1302
1303
1304
1305
1306
1307
1308
1309
1310
1311
1312
1313
1314
1315
1316
1317
1318
1319
1320
1321
1322
1323
1324
1325
1326
1327
1328
1329
1330
1331
1332
1333
1334
1335
1336
1337
1338
1339
1340
1341
1342
1343
1344
1345
1346
1347
1348
1349
1350
1351
1352
1353
1354
1355
1356
1357
1358
1359
1360
1361
1362
1363
1364
1365
1366
1367
1368
1369
1370
1371
1372
1373
1374
1375
1376
1377
1378
1379
1380
1381
1382
1383
1384
1385
1386
1387
1388
1389
1390
1391
1392
1393
1394
1395
1396
1397
1398
1399
1400
1401
1402
1403
1404
1405
1406
1407
1408
1409
1410
1411
1412
1413
1414
1415
1416
1417
1418
1419
1420
1421
1422
1423
1424
1425
1426
1427
1428
1429
1430
1431
1432
1433
1434
1435
1436
1437
1438
1439
1440
1441
1442
1443
1444
1445
1446
1447
1448
1449
1450
1451
1452
1453
1454
1455
1456
1457
1458
1459
1460
1461
1462
1463
1464
1465
1466
1467
1468
1469
1470
1471
1472
1473
1474
1475
1476
1477
1478
1479
1480
1481
1482
1483
1484
1485
1486
1487
1488
1489
1490
1491
1492
1493
1494
1495
1496
1497
1498
1499
1500
1501
1502
1503
1504
1505
1506
1507
1508
1509
1510
1511
1512
1513
1514
1515
1516
1517
1518
1519
1520
1521
1522
1523
1524
1525
1526
1527
1528
1529
1530
1531
1532
1533
1534
1535
1536
1537
1538
1539
1540
1541
1542
1543
1544
1545
1546
1547
1548
1549
1550
1551
1552
1553
1554
1555
1556
1557
1558
1559
1560
1561
1562
1563
1564
1565
1566
1567
1568
1569
1570
1571
1572
1573
1574
1575
1576
1577
1578
1579
1580
1581
1582
1583
1584
1585
1586
1587
1588
1589
1590
1591
1592
1593
1594
1595
1596
1597
1598
1599
1600
1601
1602
1603
1604
1605
1606
1607
1608
1609
1610
1611
1612
1613
1614
1615
1616
1617
1618
1619
1620
1621
1622
1623
1624
1625
1626
1627
1628
1629
1630
1631
1632
1633
1634
1635
1636
1637
1638
1639
1640
1641
1642
1643
1644
1645
1646
1647
1648
1649
1650
1651
1652
1653
1654
1655
1656
1657
1658
1659
1660
1661
1662
1663
1664
1665
1666
1667
1668
1669
1670
1671
1672
1673
1674
1675
1676
1677
1678
1679
1680
1681
1682
1683
1684
1685
1686
1687
1688
1689
1690
1691
1692
1693
1694
1695
1696
1697
1698
1699
1700
1701
1702
1703
1704
1705
1706
1707
1708
1709
1710
1711
1712
1713
1714
1715
1716
1717
1718
1719
1720
1721
1722
1723
1724
1725
1726
1727
1728
1729
1730
1731
1732
1733
1734
1735
1736
1737
1738
1739
1740
1741
1742
1743
1744
1745
1746
1747
1748
1749
1750
1751
1752
1753
1754
1755
1756
1757
1758
1759
1760
1761
1762
1763
1764
1765
#include "config.h"
#include "doh.hh"

#ifdef HAVE_DNS_OVER_HTTPS
#define H2O_USE_EPOLL 1

#include <cerrno>
#include <iostream>
#include <thread>

#include <boost/algorithm/string.hpp>
#include <h2o.h>
//#include <h2o/http1.h>
#include <h2o/http2.h>

#include <openssl/err.h>
#include <openssl/ssl.h>

#include "base64.hh"
#include "dnsname.hh"
#undef CERT
#include "dnsdist.hh"
#include "dnsdist-tcp.hh"
#include "misc.hh"
#include "dns.hh"
#include "dolog.hh"
#include "dnsdist-concurrent-connections.hh"
#include "dnsdist-ecs.hh"
#include "dnsdist-proxy-protocol.hh"
#include "dnsdist-rules.hh"
#include "dnsdist-xpf.hh"
#include "libssl.hh"
#include "threadname.hh"

/* So, how does this work. We use h2o for our http2 and TLS needs.
   If the operator has configured multiple IP addresses to listen on,
   we launch multiple h2o listener threads. We can hook in to multiple
   URLs though on the same IP. There is no SNI yet (I think).

   h2o is event driven, so we get callbacks if a new DNS query arrived.
   When it does, we do some minimal parsing on it, and send it on to the
   dnsdist worker thread which we also launched.

   This dnsdist worker thread injects the query into the normal dnsdist flow
   (over a pipe). The response also goes back over a (different) pipe,
   where we pick it up and deliver it back to h2o.

   For coordination, we use the h2o socket multiplexer, which is sensitive to our
   pipe too.
*/

/* h2o notes.
   Paths and parameters etc just *happen* to be null-terminated in HTTP2.
   They are not in HTTP1. So you MUST use the length field!
*/

/* 'Intermediate' compatibility from https://wiki.mozilla.org/Security/Server_Side_TLS#Intermediate_compatibility_.28default.29 */
#define DOH_DEFAULT_CIPHERS "ECDHE-ECDSA-CHACHA20-POLY1305:ECDHE-RSA-CHACHA20-POLY1305:ECDHE-ECDSA-AES128-GCM-SHA256:ECDHE-RSA-AES128-GCM-SHA256:ECDHE-ECDSA-AES256-GCM-SHA384:ECDHE-RSA-AES256-GCM-SHA384:DHE-RSA-AES128-GCM-SHA256:DHE-RSA-AES256-GCM-SHA384:ECDHE-ECDSA-AES128-SHA256:ECDHE-RSA-AES128-SHA256:ECDHE-ECDSA-AES128-SHA:ECDHE-RSA-AES256-SHA384:ECDHE-RSA-AES128-SHA:ECDHE-ECDSA-AES256-SHA384:ECDHE-ECDSA-AES256-SHA:ECDHE-RSA-AES256-SHA:DHE-RSA-AES128-SHA256:DHE-RSA-AES128-SHA:DHE-RSA-AES256-SHA256:DHE-RSA-AES256-SHA:ECDHE-ECDSA-DES-CBC3-SHA:ECDHE-RSA-DES-CBC3-SHA:EDH-RSA-DES-CBC3-SHA:AES128-GCM-SHA256:AES256-GCM-SHA384:AES128-SHA256:AES256-SHA256:AES128-SHA:AES256-SHA:DES-CBC3-SHA:!DSS"

class DOHAcceptContext
{
public:
  DOHAcceptContext()
  {
    memset(&d_h2o_accept_ctx, 0, sizeof(d_h2o_accept_ctx));
    d_rotatingTicketsKey.clear();
  }
  DOHAcceptContext(const DOHAcceptContext&) = delete;
  DOHAcceptContext& operator=(const DOHAcceptContext&) = delete;

  h2o_accept_ctx_t* get()
  {
    return &d_h2o_accept_ctx;
  }

  ~DOHAcceptContext()
  {
    SSL_CTX_free(d_h2o_accept_ctx.ssl_ctx);
    d_h2o_accept_ctx.ssl_ctx = nullptr;
  }

  void decrementConcurrentConnections()
  {
    if (d_cs != nullptr) {
      --d_cs->tcpCurrentConnections;
    }
  }

  time_t getNextTicketsKeyRotation() const
  {
    return d_ticketsKeyNextRotation;
  }

  size_t getTicketsKeysCount() const
  {
    size_t res = 0;
    if (d_ticketKeys) {
      res = d_ticketKeys->getKeysCount();
    }
    return res;
  }

  void rotateTicketsKey(time_t now)
  {
    if (!d_ticketKeys) {
      return;
    }

    d_ticketKeys->rotateTicketsKey(now);

    if (d_ticketsKeyRotationDelay > 0) {
      d_ticketsKeyNextRotation = now + d_ticketsKeyRotationDelay;
    }
  }

  void loadTicketsKeys(const std::string& keyFile)
  {
    if (!d_ticketKeys) {
      return;
    }
    d_ticketKeys->loadTicketsKeys(keyFile);

    if (d_ticketsKeyRotationDelay > 0) {
      d_ticketsKeyNextRotation = time(nullptr) + d_ticketsKeyRotationDelay;
    }
  }

  void handleTicketsKeyRotation()
  {
    if (d_ticketsKeyRotationDelay == 0) {
      return;
    }

    time_t now = time(nullptr);
    if (now > d_ticketsKeyNextRotation) {
      if (d_rotatingTicketsKey.test_and_set()) {
        /* someone is already rotating */
        return;
      }
      try {
        rotateTicketsKey(now);

        d_rotatingTicketsKey.clear();
      }
      catch(const std::runtime_error& e) {
        d_rotatingTicketsKey.clear();
        throw std::runtime_error(std::string("Error generating a new tickets key for TLS context:") + e.what());
      }
      catch(...) {
        d_rotatingTicketsKey.clear();
        throw;
      }
    }
  }

  std::map<int, std::string> d_ocspResponses;
  std::unique_ptr<OpenSSLTLSTicketKeysRing> d_ticketKeys{nullptr};
  std::unique_ptr<FILE, int(*)(FILE*)> d_keyLogFile{nullptr, fclose};
  ClientState* d_cs{nullptr};
  time_t d_ticketsKeyRotationDelay{0};

private:
  h2o_accept_ctx_t d_h2o_accept_ctx;
  std::atomic<uint64_t> d_refcnt{1};
  time_t d_ticketsKeyNextRotation{0};
  std::atomic_flag d_rotatingTicketsKey;
};

// we create one of these per thread, and pass around a pointer to it
// through the bowels of h2o
struct DOHServerConfig
{
  DOHServerConfig(uint32_t idleTimeout, uint32_t internalPipeBufferSize): accept_ctx(std::make_shared<DOHAcceptContext>())
  {
    int fd[2];
#ifndef USE_SINGLE_ACCEPTOR_THREAD
    if (pipe(fd) < 0) {
      unixDie("Creating a pipe for DNS over HTTPS");
    }
    dohquerypair[0] = fd[1];
    dohquerypair[1] = fd[0];

    setNonBlocking(dohquerypair[0]);
    if (internalPipeBufferSize > 0) {
      setPipeBufferSize(dohquerypair[0], internalPipeBufferSize);
    }
#endif /* USE_SINGLE_ACCEPTOR_THREAD */

    if (pipe(fd) < 0) {
#ifndef USE_SINGLE_ACCEPTOR_THREAD
      close(dohquerypair[0]);
      close(dohquerypair[1]);
#endif /* USE_SINGLE_ACCEPTOR_THREAD */
      unixDie("Creating a pipe for DNS over HTTPS");
    }

    dohresponsepair[0] = fd[1];
    dohresponsepair[1] = fd[0];

    setNonBlocking(dohresponsepair[0]);
    if (internalPipeBufferSize > 0) {
      setPipeBufferSize(dohresponsepair[0], internalPipeBufferSize);
    }

    setNonBlocking(dohresponsepair[1]);

    h2o_config_init(&h2o_config);
    h2o_config.http2.idle_timeout = idleTimeout * 1000;
    /* if you came here for a way to make the number of concurrent streams (concurrent requests per connection)
       configurable, or even just bigger, I have bad news for you.
       h2o_config.http2.max_concurrent_requests_per_connection (default of 100) is capped by
       H2O_HTTP2_SETTINGS_HOST.max_concurrent_streams which is not configurable. Even if decided to change the
       hard-coded value, libh2o's author warns that there might be parts of the code where the stream ID is stored
       in 8 bits, making 256 a hard value: https://github.com/h2o/h2o/issues/805
    */
  }
  DOHServerConfig(const DOHServerConfig&) = delete;
  DOHServerConfig& operator=(const DOHServerConfig&) = delete;

  LocalHolders holders;
  std::set<std::string, std::less<>> paths;
  h2o_globalconf_t h2o_config;
  h2o_context_t h2o_ctx;
  std::shared_ptr<DOHAcceptContext> accept_ctx{nullptr};
  ClientState* cs{nullptr};
  std::shared_ptr<DOHFrontend> df{nullptr};
#ifndef USE_SINGLE_ACCEPTOR_THREAD
  int dohquerypair[2]{-1,-1};
#endif /* USE_SINGLE_ACCEPTOR_THREAD */
  int dohresponsepair[2]{-1,-1};
};

/* This internal function sends back the object to the main thread to send a reply.
   The caller should NOT release or touch the unit after calling this function */
static void sendDoHUnitToTheMainThread(DOHUnitUniquePtr&& du, const char* description)
{
  /* taking a naked pointer since we are about to send that pointer over a pipe */
  auto ptr = du.release();
  /* increasing the reference counter. This should not be strictly needed because
     we already hold a reference and will only release it if we failed to send the
     pointer over the pipe, but TSAN seems confused when the responder thread gets
     a reply from a backend before the send() syscall sending the corresponding query
     to that backend has returned in the initial thread.
     The memory barrier needed to increase that counter seems to work around that.
  */
  ptr->get();
  static_assert(sizeof(ptr) <= PIPE_BUF, "Writes up to PIPE_BUF are guaranteed not to be interleaved and to either fully succeed or fail");

  ssize_t sent = write(ptr->rsock, &ptr, sizeof(ptr));
  if (sent != sizeof(ptr)) {
    if (errno == EAGAIN || errno == EWOULDBLOCK) {
      ++g_stats.dohResponsePipeFull;
      vinfolog("Unable to pass a %s to the DoH worker thread because the pipe is full", description);
    }
    else {
      vinfolog("Unable to pass a %s to the DoH worker thread because we couldn't write to the pipe: %s", description, stringerror());
    }

    /* we fail to write over the pipe so we do not need to hold to that ref anymore */
    ptr->release();
  }
  /* we decrement the counter incremented above at the beginning of that function */
  ptr->release();
}

/* This function is called from other threads than the main DoH one,
   instructing it to send a 502 error to the client.
   It takes ownership of the unit. */
void handleDOHTimeout(DOHUnitUniquePtr&& oldDU)
{
  if (oldDU == nullptr) {
    return;
  }

  /* we are about to erase an existing DU */
  oldDU->status_code = 502;

  sendDoHUnitToTheMainThread(std::move(oldDU), "DoH timeout");
}

struct DOHConnection
{
  std::shared_ptr<DOHAcceptContext> d_acceptCtx{nullptr};
  ComboAddress d_remote;
  ComboAddress d_local;
  struct timeval d_connectionStartTime{0, 0};
  size_t d_nbQueries{0};
  int d_desc{-1};
};

static thread_local std::unordered_map<int, DOHConnection> t_conns;

static void on_socketclose(void *data)
{
  auto conn = reinterpret_cast<DOHConnection*>(data);
  if (conn != nullptr) {
    if (conn->d_acceptCtx) {
      struct timeval now;
      gettimeofday(&now, nullptr);

      auto diff = now - conn->d_connectionStartTime;

      conn->d_acceptCtx->decrementConcurrentConnections();
      conn->d_acceptCtx->d_cs->updateTCPMetrics(conn->d_nbQueries, diff.tv_sec * 1000 + diff.tv_usec / 1000);
    }

    dnsdist::IncomingConcurrentTCPConnectionsManager::accountClosedTCPConnection(conn->d_remote);
    // you can no longer touch conn, or data, after this call
    t_conns.erase(conn->d_desc);
  }
}

static const std::string& getReasonFromStatusCode(uint16_t statusCode)
{
  /* no need to care too much about this, HTTP/2 has no 'reason' anyway */
  static const std::unordered_map<uint16_t, std::string> reasons = {
    { 200, "OK" },
    { 301, "Moved Permanently" },
    { 302, "Found" },
    { 303, "See Other" },
    { 304, "Not Modified" },
    { 305, "Use Proxy" },
    { 306, "Switch Proxy" },
    { 307, "Temporary Redirect" },
    { 308, "Permanent Redirect" },
    { 400, "Bad Request" },
    { 401, "Unauthorized" },
    { 402, "Payment Required" },
    { 403, "Forbidden" },
    { 404, "Not Found" },
    { 405, "Method Not Allowed" },
    { 406, "Not Acceptable" },
    { 407, "Proxy Authentication Required" },
    { 408, "Request Timeout" },
    { 409, "Conflict" },
    { 410, "Gone" },
    { 411, "Length Required" },
    { 412, "Precondition Failed" },
    { 413, "Payload Too Large" },
    { 414, "URI Too Long" },
    { 415, "Unsupported Media Type" },
    { 416, "Range Not Satisfiable" },
    { 417, "Expectation Failed" },
    { 418, "I'm a teapot" },
    { 451, "Unavailable For Legal Reasons" },
    { 500, "Internal Server Error" },
    { 501, "Not Implemented" },
    { 502, "Bad Gateway" },
    { 503, "Service Unavailable" },
    { 504, "Gateway Timeout" },
    { 505, "HTTP Version Not Supported" }
  };
  static const std::string unknown = "Unknown";

  const auto it = reasons.find(statusCode);
  if (it == reasons.end()) {
    return unknown;
  }
  else {
    return it->second;
  }
}

/* Always called from the main DoH thread */
static void handleResponse(DOHFrontend& df, st_h2o_req_t* req, uint16_t statusCode, const PacketBuffer& response, const std::unordered_map<std::string, std::string>& customResponseHeaders, const std::string& contentType, bool addContentType)
{
  constexpr int overwrite_if_exists = 1;
  constexpr int maybe_token = 1;
  for (auto const& headerPair : customResponseHeaders) {
    h2o_set_header_by_str(&req->pool, &req->res.headers, headerPair.first.c_str(), headerPair.first.size(), maybe_token, headerPair.second.c_str(), headerPair.second.size(), overwrite_if_exists);
  }

  if (statusCode == 200) {
    ++df.d_validresponses;
    req->res.status = 200;

    if (addContentType) {
      if (contentType.empty()) {
        h2o_add_header(&req->pool, &req->res.headers, H2O_TOKEN_CONTENT_TYPE, nullptr, H2O_STRLIT("application/dns-message"));
      }
      else {
        /* we need to duplicate the header content because h2o keeps a pointer and we will be deleted before the response has been sent */
        h2o_iovec_t ct = h2o_strdup(&req->pool, contentType.c_str(), contentType.size());
        h2o_add_header(&req->pool, &req->res.headers, H2O_TOKEN_CONTENT_TYPE, nullptr, ct.base, ct.len);
      }
    }

    if (df.d_sendCacheControlHeaders && response.size() > sizeof(dnsheader)) {
      uint32_t minTTL = getDNSPacketMinTTL(reinterpret_cast<const char*>(response.data()), response.size());
      if (minTTL != std::numeric_limits<uint32_t>::max()) {
        std::string cacheControlValue = "max-age=" + std::to_string(minTTL);
        /* we need to duplicate the header content because h2o keeps a pointer and we will be deleted before the response has been sent */
        h2o_iovec_t ccv = h2o_strdup(&req->pool, cacheControlValue.c_str(), cacheControlValue.size());
        h2o_add_header(&req->pool, &req->res.headers, H2O_TOKEN_CACHE_CONTROL, nullptr, ccv.base, ccv.len);
      }
    }

    req->res.content_length = response.size();
    h2o_send_inline(req, reinterpret_cast<const char*>(response.data()), response.size());
  }
  else if (statusCode >= 300 && statusCode < 400) {
    /* in that case the response is actually a URL */
    /* we need to duplicate the URL because h2o uses it for the location header, keeping a pointer, and we will be deleted before the response has been sent */
    h2o_iovec_t url = h2o_strdup(&req->pool, reinterpret_cast<const char*>(response.data()), response.size());
    h2o_send_redirect(req, statusCode, getReasonFromStatusCode(statusCode).c_str(), url.base, url.len);
    ++df.d_redirectresponses;
  }
  else {
    // we need to make sure it's null-terminated */
    if (!response.empty() && response.at(response.size() - 1) == 0) {
      h2o_send_error_generic(req, statusCode, getReasonFromStatusCode(statusCode).c_str(), reinterpret_cast<const char*>(response.data()), H2O_SEND_ERROR_KEEP_HEADERS);
    }
    else {
      switch(statusCode) {
      case 400:
        h2o_send_error_400(req, getReasonFromStatusCode(statusCode).c_str(), "invalid DNS query" , 0);
        break;
      case 403:
        h2o_send_error_403(req, getReasonFromStatusCode(statusCode).c_str(), "dns query not allowed", 0);
        break;
      case 502:
        h2o_send_error_502(req, getReasonFromStatusCode(statusCode).c_str(), "no downstream server available", 0);
        break;
      case 500:
        /* fall-through */
      default:
        h2o_send_error_500(req, getReasonFromStatusCode(statusCode).c_str(), "Internal Server Error", 0);
        break;
      }
    }

    ++df.d_errorresponses;
  }
}

class DoHTCPCrossQuerySender : public TCPQuerySender
{
public:
  DoHTCPCrossQuerySender()
  {
  }

  bool active() const override
  {
    return true;
  }

  void handleResponse(const struct timeval& now, TCPResponse&& response) override
  {
    if (!response.d_idstate.du) {
      return;
    }

    auto du = std::move(response.d_idstate.du);
    if (du->rsock == -1) {
      return;
    }

    du->response = std::move(response.d_buffer);
    du->ids = std::move(response.d_idstate);
    DNSResponse dr(du->ids, du->response, du->downstream);

    dnsheader cleartextDH;
    memcpy(&cleartextDH, dr.getHeader(), sizeof(cleartextDH));

    if (!response.isAsync()) {
      static thread_local LocalStateHolder<vector<DNSDistResponseRuleAction>> localRespRuleActions = g_respruleactions.getLocal();
      static thread_local LocalStateHolder<vector<DNSDistResponseRuleAction>> localCacheInsertedRespRuleActions = g_cacheInsertedRespRuleActions.getLocal();

      dr.ids.du = std::move(du);

      if (!processResponse(dr.ids.du->response, *localRespRuleActions, *localCacheInsertedRespRuleActions, dr, false)) {
        if (dr.ids.du) {
          dr.ids.du->status_code = 503;
          sendDoHUnitToTheMainThread(std::move(dr.ids.du), "Response dropped by rules");
        }
        return;
      }

      if (dr.isAsynchronous()) {
        return;
      }

      du = std::move(dr.ids.du);
    }

    if (!du->ids.selfGenerated) {
      double udiff = du->ids.queryRealTime.udiff();
      vinfolog("Got answer from %s, relayed to %s (https), took %f usec", du->downstream->d_config.remote.toStringWithPort(), du->ids.origRemote.toStringWithPort(), udiff);

      auto backendProtocol = du->downstream->getProtocol();
      if (backendProtocol == dnsdist::Protocol::DoUDP && du->tcp) {
        backendProtocol = dnsdist::Protocol::DoTCP;
      }
      handleResponseSent(du->ids, udiff, du->ids.origRemote, du->downstream->d_config.remote, du->response.size(), cleartextDH, backendProtocol, true);
    }

    ++g_stats.responses;
    if (du->ids.cs) {
      ++du->ids.cs->responses;
    }

    sendDoHUnitToTheMainThread(std::move(du), "cross-protocol response");
  }

  void handleXFRResponse(const struct timeval& now, TCPResponse&& response) override
  {
    return handleResponse(now, std::move(response));
  }

  void notifyIOError(InternalQueryState&& query, const struct timeval& now) override
  {
    if (!query.du) {
      return;
    }

    if (query.du->rsock == -1) {
      return;
    }

    auto du = std::move(query.du);
    du->ids = std::move(query);
    du->status_code = 502;
    sendDoHUnitToTheMainThread(std::move(du), "cross-protocol error response");
  }
};

class DoHCrossProtocolQuery : public CrossProtocolQuery
{
public:
  DoHCrossProtocolQuery(DOHUnitUniquePtr&& du, bool isResponse)
  {
    if (isResponse) {
      /* happens when a response becomes async */
      query = InternalQuery(std::move(du->response), std::move(du->ids));
    }
    else {
      /* we need to duplicate the query here because we might need
         the existing query later if we get a truncated answer */
      query = InternalQuery(PacketBuffer(du->query), std::move(du->ids));
    }

    /* it might have been moved when we moved du->ids */
    if (du) {
      query.d_idstate.du = std::move(du);
    }

    /* we _could_ remove it from the query buffer and put in query's d_proxyProtocolPayload,
       clearing query.d_proxyProtocolPayloadAdded and du->proxyProtocolPayloadSize.
       Leave it for now because we know that the onky case where the payload has been
       added is when we tried over UDP, got a TC=1 answer and retried over TCP/DoT,
       and we know the TCP/DoT code can handle it. */
    query.d_proxyProtocolPayloadAdded = query.d_idstate.du->proxyProtocolPayloadSize > 0;
    downstream = query.d_idstate.du->downstream;
    proxyProtocolPayloadSize = query.d_idstate.du->proxyProtocolPayloadSize;
  }

  void handleInternalError()
  {
    query.d_idstate.du->status_code = 502;
    sendDoHUnitToTheMainThread(std::move(query.d_idstate.du), "DoH internal error");
  }

  std::shared_ptr<TCPQuerySender> getTCPQuerySender() override
  {
    query.d_idstate.du->downstream = downstream;
    return s_sender;
  }

  DNSQuestion getDQ() override
  {
    auto& ids = query.d_idstate;
    DNSQuestion dq(ids, query.d_buffer);
    return dq;
  }

  DNSResponse getDR() override
  {
    auto& ids = query.d_idstate;
    DNSResponse dr(ids, query.d_buffer, downstream);
    return dr;
   }

  DOHUnitUniquePtr&& releaseDU()
  {
    return std::move(query.d_idstate.du);
  }

private:
  static std::shared_ptr<DoHTCPCrossQuerySender> s_sender;
};

std::shared_ptr<DoHTCPCrossQuerySender> DoHCrossProtocolQuery::s_sender = std::make_shared<DoHTCPCrossQuerySender>();

std::unique_ptr<CrossProtocolQuery> getDoHCrossProtocolQueryFromDQ(DNSQuestion& dq, bool isResponse)
{
  if (!dq.ids.du) {
    throw std::runtime_error("Trying to create a DoH cross protocol query without a valid DoH unit");
  }

  auto du = std::move(dq.ids.du);
  if (&dq.ids != &du->ids) {
   du->ids = std::move(dq.ids);
  }

  du->ids.origID = dq.getHeader()->id;

  if (!isResponse) {
    if (du->query.data() != dq.getMutableData().data()) {
      du->query = std::move(dq.getMutableData());
    }
  }
  else {
    if (du->response.data() != dq.getMutableData().data()) {
      du->response = std::move(dq.getMutableData());
    }
  }

  return std::make_unique<DoHCrossProtocolQuery>(std::move(du), isResponse);
}

/*
   We are not in the main DoH thread but in the DoH 'client' thread.
*/
static void processDOHQuery(DOHUnitUniquePtr&& unit, bool inMainThread = false)
{
  const auto handleImmediateResponse = [inMainThread](DOHUnitUniquePtr&& du, const char* reason) {
    if (inMainThread) {
      handleResponse(*du->dsc->df, du->req, du->status_code, du->response, du->dsc->df->d_customResponseHeaders, du->contentType, true);
      /* so the unique pointer is stored in the InternalState which itself is stored in the unique pointer itself. We likely need
         a better design, but for now let's just reset the internal one since we know it is no longer needed. */
      du->ids.du.reset();
    }
    else {
      sendDoHUnitToTheMainThread(std::move(du), reason);
    }
  };

  auto& ids = unit->ids;
  ids.du = std::move(unit);
  auto& du = ids.du;
  uint16_t queryId = 0;
  ComboAddress remote;

  try {
    if (!du->req) {
      // we got closed meanwhile. XXX small race condition here
      // but we should be fine as long as we don't touch du->req
      // outside of the main DoH thread
      du->status_code = 500;
      handleImmediateResponse(std::move(du), "DoH killed in flight");
      return;
    }

    {
      // if there was no EDNS, we add it with a large buffer size
      // so we can use UDP to talk to the backend.
      auto dh = const_cast<struct dnsheader*>(reinterpret_cast<const struct dnsheader*>(du->query.data()));

      if (!dh->arcount) {
        if (generateOptRR(std::string(), du->query, 4096, 4096, 0, false)) {
          dh = const_cast<struct dnsheader*>(reinterpret_cast<const struct dnsheader*>(du->query.data())); // may have reallocated
          dh->arcount = htons(1);
          du->ids.ednsAdded = true;
        }
      }
      else {
        // we leave existing EDNS in place
      }
    }

    remote = du->ids.origRemote;
    DOHServerConfig* dsc = du->dsc;
    auto& holders = dsc->holders;
    ClientState& cs = *dsc->cs;

    if (du->query.size() < sizeof(dnsheader)) {
      ++g_stats.nonCompliantQueries;
      ++cs.nonCompliantQueries;
      du->status_code = 400;
      handleImmediateResponse(std::move(du), "DoH non-compliant query");
      return;
    }

    ++cs.queries;
    ++g_stats.queries;
    du->ids.queryRealTime.start();

    {
      /* don't keep that pointer around, it will be invalidated if the buffer is ever resized */
      struct dnsheader* dh = reinterpret_cast<struct dnsheader*>(du->query.data());

      if (!checkQueryHeaders(dh, cs)) {
        du->status_code = 400;
        handleImmediateResponse(std::move(du), "DoH invalid headers");
        return;
      }

      if (dh->qdcount == 0) {
        dh->rcode = RCode::NotImp;
        dh->qr = true;
        du->response = std::move(du->query);

        handleImmediateResponse(std::move(du), "DoH empty query");
        return;
      }

      queryId = ntohs(dh->id);
    }

    auto downstream = du->downstream;
    du->ids.qname = DNSName(reinterpret_cast<const char*>(du->query.data()), du->query.size(), sizeof(dnsheader), false, &du->ids.qtype, &du->ids.qclass);
    DNSQuestion dq(du->ids, du->query);
    const uint16_t* flags = getFlagsFromDNSHeader(dq.getHeader());
    ids.origFlags = *flags;
    du->ids.cs = &cs;
    dq.sni = std::move(du->sni);

    auto result = processQuery(dq, holders, downstream);

    if (result == ProcessQueryResult::Drop) {
      du->status_code = 403;
      handleImmediateResponse(std::move(du), "DoH dropped query");
      return;
    }
    else if (result == ProcessQueryResult::Asynchronous) {
      return;
    }
    else if (result == ProcessQueryResult::SendAnswer) {
      if (du->response.empty()) {
        du->response = std::move(du->query);
      }
      if (du->response.size() >= sizeof(dnsheader) && du->contentType.empty()) {
        auto dh = reinterpret_cast<const struct dnsheader*>(du->response.data());

        handleResponseSent(du->ids.qname, QType(du->ids.qtype), 0., du->ids.origDest, ComboAddress(), du->response.size(), *dh, dnsdist::Protocol::DoH, dnsdist::Protocol::DoH, false);
      }
      handleImmediateResponse(std::move(du), "DoH self-answered response");
      return;
    }

    if (result != ProcessQueryResult::PassToBackend) {
      du->status_code = 500;
      handleImmediateResponse(std::move(du), "DoH no backend available");
      return;
    }

    if (downstream == nullptr) {
      du->status_code = 502;
      handleImmediateResponse(std::move(du), "DoH no backend available");
      return;
    }

    du->downstream = downstream;

    if (downstream->isTCPOnly()) {
      std::string proxyProtocolPayload;
      /* we need to do this _before_ creating the cross protocol query because
         after that the buffer will have been moved */
      if (downstream->d_config.useProxyProtocol) {
        proxyProtocolPayload = getProxyProtocolPayload(dq);
      }

      du->ids.origID = htons(queryId);
      du->tcp = true;

      /* this moves du->ids, careful! */
      auto cpq = std::make_unique<DoHCrossProtocolQuery>(std::move(du), false);
      cpq->query.d_proxyProtocolPayload = std::move(proxyProtocolPayload);

      if (downstream->passCrossProtocolQuery(std::move(cpq))) {
        return;
      }
      else {
        if (inMainThread) {
          du = cpq->releaseDU();
          du->status_code = 502;
          handleImmediateResponse(std::move(du), "DoH internal error");
        }
        else {
          cpq->handleInternalError();
        }
        return;
      }
    }

    ComboAddress dest = dq.ids.origDest;
    if (!assignOutgoingUDPQueryToBackend(downstream, htons(queryId), dq, du->query, dest)) {
      du->status_code = 502;
      handleImmediateResponse(std::move(du), "DoH internal error");
      return;
    }
  }
  catch (const std::exception& e) {
    vinfolog("Got an error in DOH question thread while parsing a query from %s, id %d: %s", remote.toStringWithPort(), queryId, e.what());
    du->status_code = 500;
    handleImmediateResponse(std::move(du), "DoH internal error");
    return;
  }

  return;
}

/* called when a HTTP response is about to be sent, from the main DoH thread */
static void on_response_ready_cb(struct st_h2o_filter_t *self, h2o_req_t *req, h2o_ostream_t **slot)
{
  if (req == nullptr) {
    return;
  }

  DOHServerConfig* dsc = reinterpret_cast<DOHServerConfig*>(req->conn->ctx->storage.entries[0].data);

  DOHFrontend::HTTPVersionStats* stats = nullptr;
  if (req->version < 0x200) {
    /* HTTP 1.x */
    stats = &dsc->df->d_http1Stats;
  }
  else {
    /* HTTP 2.0 */
    stats = &dsc->df->d_http2Stats;
  }

  switch (req->res.status) {
  case 200:
    ++stats->d_nb200Responses;
    break;
  case 400:
    ++stats->d_nb400Responses;
    break;
  case 403:
    ++stats->d_nb403Responses;
    break;
  case 500:
    ++stats->d_nb500Responses;
    break;
  case 502:
    ++stats->d_nb502Responses;
    break;
  default:
    ++stats->d_nbOtherResponses;
    break;
  }

  h2o_setup_next_ostream(req, slot);
}

/* this is called by h2o when our request dies.
   We use this to signal to the 'du' that this req is no longer alive */
static void on_generator_dispose(void *_self)
{
  DOHUnit** du = reinterpret_cast<DOHUnit**>(_self);
  if (*du) { // if 0, on_dnsdist cleaned up du already
    (*du)->self = nullptr;
    (*du)->req = nullptr;
  }
}

/* This executes in the main DoH thread.
   We allocate a DOHUnit and send it to dnsdistclient() function in the doh client thread
   via a pipe */
static void doh_dispatch_query(DOHServerConfig* dsc, h2o_handler_t* self, h2o_req_t* req, PacketBuffer&& query, const ComboAddress& local, const ComboAddress& remote, std::string&& path)
{
  try {
    /* we only parse it there as a sanity check, we will parse it again later */
    DNSPacketMangler mangler(reinterpret_cast<char*>(query.data()), query.size());
    mangler.skipDomainName();
    mangler.skipBytes(4);

    /* we are doing quite some copies here, sorry about that,
       but we can't keep accessing the req object once we are in a different thread
       because the request might get killed by h2o at pretty much any time */
    auto du = std::make_unique<DOHUnit>(std::move(query), std::move(path), std::string(req->authority.base, req->authority.len));
    du->dsc = dsc;
    du->req = req;
    du->ids.origDest = local;
    du->ids.origRemote = remote;
    du->ids.protocol = dnsdist::Protocol::DoH;
    du->rsock = dsc->dohresponsepair[0];
    if (req->scheme != nullptr) {
      du->scheme = std::string(req->scheme->name.base, req->scheme->name.len);
    }
    du->query_at = req->query_at;

    if (dsc->df->d_keepIncomingHeaders) {
      du->headers = std::make_unique<std::unordered_map<std::string, std::string>>();
      du->headers->reserve(req->headers.size);
      for (size_t i = 0; i < req->headers.size; ++i) {
        (*du->headers)[std::string(req->headers.entries[i].name->base, req->headers.entries[i].name->len)] = std::string(req->headers.entries[i].value.base, req->headers.entries[i].value.len);
      }
    }

#ifdef HAVE_H2O_SOCKET_GET_SSL_SERVER_NAME
    h2o_socket_t* sock = req->conn->callbacks->get_socket(req->conn);
    const char * sni = h2o_socket_get_ssl_server_name(sock);
    if (sni != nullptr) {
      du->sni = sni;
    }
#endif /* HAVE_H2O_SOCKET_GET_SSL_SERVER_NAME */
    du->self = reinterpret_cast<DOHUnit**>(h2o_mem_alloc_shared(&req->pool, sizeof(*self), on_generator_dispose));
    auto ptr = du.release();
    *(ptr->self) = ptr;

#ifdef USE_SINGLE_ACCEPTOR_THREAD
    processDOHQuery(DOHUnitUniquePtr(ptr, DOHUnit::release), true);
#else /* USE_SINGLE_ACCEPTOR_THREAD */
    try  {
      static_assert(sizeof(ptr) <= PIPE_BUF, "Writes up to PIPE_BUF are guaranteed not to be interleaved and to either fully succeed or fail");
      ssize_t sent = write(dsc->dohquerypair[0], &ptr, sizeof(ptr));
      if (sent != sizeof(ptr)) {
        if (errno == EAGAIN || errno == EWOULDBLOCK) {
          ++g_stats.dohQueryPipeFull;
          vinfolog("Unable to pass a DoH query to the DoH worker thread because the pipe is full");
        }
        else {
          vinfolog("Unable to pass a DoH query to the DoH worker thread because we couldn't write to the pipe: %s", stringerror());
        }
        ptr->release();
        ptr = nullptr;
        h2o_send_error_500(req, "Internal Server Error", "Internal Server Error", 0);
      }
    }
    catch (...) {
      if (ptr != nullptr) {
        ptr->release();
      }
    }
#endif /* USE_SINGLE_ACCEPTOR_THREAD */
  }
  catch (const std::exception& e) {
    vinfolog("Had error parsing DoH DNS packet from %s: %s", remote.toStringWithPort(), e.what());
    h2o_send_error_400(req, "Bad Request", "The DNS query could not be parsed", 0);
  }
}

/* can only be called from the main DoH thread */
static bool getHTTPHeaderValue(const h2o_req_t* req, const std::string& headerName, std::string_view& value)
{
  bool found = false;
  /* early versions of boost::string_ref didn't have the ability to compare to string */
  std::string_view headerNameView(headerName);

  for (size_t i = 0; i < req->headers.size; ++i) {
    if (std::string_view(req->headers.entries[i].name->base, req->headers.entries[i].name->len) == headerNameView) {
      value = std::string_view(req->headers.entries[i].value.base, req->headers.entries[i].value.len);
      /* don't stop there, we might have more than one header with the same name, and we want the last one */
      found = true;
    }
  }

  return found;
}

/* can only be called from the main DoH thread */
static std::optional<ComboAddress> processForwardedForHeader(const h2o_req_t* req, const ComboAddress& remote)
{
  static const std::string headerName = "x-forwarded-for";
  std::string_view value;

  if (getHTTPHeaderValue(req, headerName, value)) {
    try {
      auto pos = value.rfind(',');
      if (pos != std::string_view::npos) {
        ++pos;
        for (; pos < value.size() && value[pos] == ' '; ++pos)
        {
        }

        if (pos < value.size()) {
          value = value.substr(pos);
        }
      }
      return ComboAddress(std::string(value));
    }
    catch (const std::exception& e) {
      vinfolog("Invalid X-Forwarded-For header ('%s') received from %s : %s", std::string(value), remote.toStringWithPort(), e.what());
    }
    catch (const PDNSException& e) {
      vinfolog("Invalid X-Forwarded-For header ('%s') received from %s : %s", std::string(value), remote.toStringWithPort(), e.reason);
    }
  }

  return std::nullopt;
}

/*
  A query has been parsed by h2o, this executes in the main DoH thread.
  For GET, the base64url-encoded payload is in the 'dns' parameter, which might be the first parameter, or not.
  For POST, the payload is the payload.
 */
static int doh_handler(h2o_handler_t *self, h2o_req_t *req)
{
  try {
    if (!req->conn->ctx->storage.size) {
      return 0; // although we might was well crash on this
    }
    DOHServerConfig* dsc = reinterpret_cast<DOHServerConfig*>(req->conn->ctx->storage.entries[0].data);
    h2o_socket_t* sock = req->conn->callbacks->get_socket(req->conn);

    const int descriptor = h2o_socket_get_fd(sock);
    if (descriptor == -1) {
      return 0;
    }

    auto& conn = t_conns.at(descriptor);
    ++conn.d_nbQueries;
    if (conn.d_nbQueries == 1) {
      if (h2o_socket_get_ssl_session_reused(sock) == 0) {
        ++dsc->cs->tlsNewSessions;
      }
      else {
        ++dsc->cs->tlsResumptions;
      }

      h2o_socket_getsockname(sock, reinterpret_cast<struct sockaddr*>(&conn.d_local));
    }

    auto remote = conn.d_remote;
    if (dsc->df->d_trustForwardedForHeader) {
      auto newRemote = processForwardedForHeader(req, remote);
      if (newRemote) {
        remote = std::move(*newRemote);
      }
    }

    auto& holders = dsc->holders;
    if (!holders.acl->match(remote)) {
      ++g_stats.aclDrops;
      vinfolog("Query from %s (DoH) dropped because of ACL", remote.toStringWithPort());
      h2o_send_error_403(req, "Forbidden", "dns query not allowed because of ACL", 0);
      return 0;
    }

    if (auto tlsversion = h2o_socket_get_ssl_protocol_version(sock)) {
      if(!strcmp(tlsversion, "TLSv1.0"))
        ++dsc->cs->tls10queries;
      else if(!strcmp(tlsversion, "TLSv1.1"))
        ++dsc->cs->tls11queries;
      else if(!strcmp(tlsversion, "TLSv1.2"))
        ++dsc->cs->tls12queries;
      else if(!strcmp(tlsversion, "TLSv1.3"))
        ++dsc->cs->tls13queries;
      else
        ++dsc->cs->tlsUnknownqueries;
    }

    if (dsc->df->d_exactPathMatching) {
      const std::string_view pathOnly(req->path_normalized.base, req->path_normalized.len);
      if (dsc->paths.count(pathOnly) == 0) {
        h2o_send_error_404(req, "Not Found", "there is no endpoint configured for this path", 0);
        return 0;
      }
    }

    // would be nice to be able to use a std::string_view there,
    // but regex (called by matches() internally) requires a null-terminated string
    string path(req->path.base, req->path.len);
    /* the responses map can be updated at runtime, so we need to take a copy of
       the shared pointer, increasing the reference counter */
    auto responsesMap = dsc->df->d_responsesMap;
    /* 1 byte for the root label, 2 type, 2 class, 4 TTL (fake), 2 record length, 2 option length, 2 option code, 2 family, 1 source, 1 scope, 16 max for a full v6 */
    const size_t maxAdditionalSizeForEDNS = 35U;
    if (responsesMap) {
      for (const auto& entry : *responsesMap) {
        if (entry->matches(path)) {
          const auto& customHeaders = entry->getHeaders();
          handleResponse(*dsc->df, req, entry->getStatusCode(), entry->getContent(), customHeaders ? *customHeaders : dsc->df->d_customResponseHeaders, std::string(), false);
          return 0;
        }
      }
    }

    if (h2o_memis(req->method.base, req->method.len, H2O_STRLIT("POST"))) {
      ++dsc->df->d_postqueries;
      if(req->version >= 0x0200)
        ++dsc->df->d_http2Stats.d_nbQueries;
      else
        ++dsc->df->d_http1Stats.d_nbQueries;

      PacketBuffer query;
      /* We reserve a few additional bytes to be able to add EDNS later */
      query.reserve(req->entity.len + maxAdditionalSizeForEDNS);
      query.resize(req->entity.len);
      memcpy(query.data(), req->entity.base, req->entity.len);
      doh_dispatch_query(dsc, self, req, std::move(query), conn.d_local, remote, std::move(path));
    }
    else if(req->query_at != SIZE_MAX && (req->path.len - req->query_at > 5)) {
      auto pos = path.find("?dns=");
      if(pos == string::npos)
        pos = path.find("&dns=");
      if(pos != string::npos) {
        // need to base64url decode this
        string sdns(path.substr(pos+5));
        boost::replace_all(sdns,"-", "+");
        boost::replace_all(sdns,"_", "/");
        // re-add padding that may have been missing
        switch (sdns.size() % 4) {
        case 2:
          sdns.append(2, '=');
          break;
        case 3:
          sdns.append(1, '=');
          break;
        }

        PacketBuffer decoded;

        /* rough estimate so we hopefully don't need a new allocation later */
        /* We reserve at few additional bytes to be able to add EDNS later */
        const size_t estimate = ((sdns.size() * 3) / 4);
        decoded.reserve(estimate + maxAdditionalSizeForEDNS);
        if(B64Decode(sdns, decoded) < 0) {
          h2o_send_error_400(req, "Bad Request", "Unable to decode BASE64-URL", 0);
          ++dsc->df->d_badrequests;
          return 0;
        }
        else {
          ++dsc->df->d_getqueries;
          if(req->version >= 0x0200)
            ++dsc->df->d_http2Stats.d_nbQueries;
          else
            ++dsc->df->d_http1Stats.d_nbQueries;

          doh_dispatch_query(dsc, self, req, std::move(decoded), conn.d_local, remote, std::move(path));
        }
      }
      else
      {
        vinfolog("HTTP request without DNS parameter: %s", req->path.base);
        h2o_send_error_400(req, "Bad Request", "Unable to find the DNS parameter", 0);
        ++dsc->df->d_badrequests;
        return 0;
      }
    }
    else {
      h2o_send_error_400(req, "Bad Request", "Unable to parse the request", 0);
      ++dsc->df->d_badrequests;
    }
    return 0;
  }
  catch(const std::exception& e)
  {
    errlog("DOH Handler function failed with error %s", e.what());
    return 0;
  }
}

HTTPHeaderRule::HTTPHeaderRule(const std::string& header, const std::string& regex)
  : d_header(toLower(header)), d_regex(regex), d_visual("http[" + header+ "] ~ " + regex)
{
}

bool HTTPHeaderRule::matches(const DNSQuestion* dq) const
{
  if (!dq->ids.du || !dq->ids.du->headers) {
    return false;
  }

  for (const auto& header : *dq->ids.du->headers) {
    if (header.first == d_header) {
      return d_regex.match(header.second);
    }
  }
  return false;
}

string HTTPHeaderRule::toString() const
{
  return d_visual;
}

HTTPPathRule::HTTPPathRule(const std::string& path)
  :  d_path(path)
{

}

bool HTTPPathRule::matches(const DNSQuestion* dq) const
{
  if (!dq->ids.du) {
    return false;
  }

  if (dq->ids.du->query_at == SIZE_MAX) {
    return dq->ids.du->path == d_path;
  }
  else {
    return d_path.compare(0, d_path.size(), dq->ids.du->path, 0, dq->ids.du->query_at) == 0;
  }
}

string HTTPPathRule::toString() const
{
  return "url path == " + d_path;
}

HTTPPathRegexRule::HTTPPathRegexRule(const std::string& regex): d_regex(regex), d_visual("http path ~ " + regex)
{
}

bool HTTPPathRegexRule::matches(const DNSQuestion* dq) const
{
  if (!dq->ids.du) {
    return false;
  }

  return d_regex.match(dq->ids.du->getHTTPPath());
}

string HTTPPathRegexRule::toString() const
{
  return d_visual;
}

std::unordered_map<std::string, std::string> DOHUnit::getHTTPHeaders() const
{
  std::unordered_map<std::string, std::string> results;
  if (headers) {
    results.reserve(headers->size());

    for (const auto& header : *headers) {
      results.insert(header);
    }
  }

  return results;
}

std::string DOHUnit::getHTTPPath() const
{
  if (query_at == SIZE_MAX) {
    return path;
  }
  else {
    return std::string(path, 0, query_at);
  }
}

std::string DOHUnit::getHTTPHost() const
{
  return host;
}

std::string DOHUnit::getHTTPScheme() const
{
  return scheme;
}

std::string DOHUnit::getHTTPQueryString() const
{
  if (query_at == SIZE_MAX) {
    return std::string();
  }
  else {
    return path.substr(query_at);
  }
}

void DOHUnit::setHTTPResponse(uint16_t statusCode, PacketBuffer&& body_, const std::string& contentType_)
{
  status_code = statusCode;
  response = std::move(body_);
  if (!response.empty() && statusCode >= 400) {
    // we need to make sure it's null-terminated */
    if (response.at(response.size() - 1) != 0) {
      response.push_back(0);
    }
  }

  contentType = contentType_;
}

#ifndef USE_SINGLE_ACCEPTOR_THREAD
/* query has been parsed by h2o, which called doh_handler() in the main DoH thread.
   In order not to block for long, doh_handler() called doh_dispatch_query() which allocated
   a DOHUnit object and passed it to us */
static void dnsdistclient(int qsock)
{
  setThreadName("dnsdist/doh-cli");

  for(;;) {
    try {
      DOHUnit* ptr = nullptr;
      ssize_t got = read(qsock, &ptr, sizeof(ptr));
      if (got < 0) {
        warnlog("Error receiving internal DoH query: %s", strerror(errno));
        continue;
      }
      else if (static_cast<size_t>(got) < sizeof(ptr)) {
        continue;
      }

      DOHUnitUniquePtr du(ptr, DOHUnit::release);
      /* we are not in the main DoH thread anymore, so there is a real risk of
         a race condition where h2o kills the query while we are processing it,
         so we can't touch the content of du->req until we are back into the
         main DoH thread */
      if (!du->req) {
        // it got killed in flight already
        du->self = nullptr;
        continue;
      }

      processDOHQuery(std::move(du), false);
    }
    catch (const std::exception& e) {
      errlog("Error while processing query received over DoH: %s", e.what());
    }
    catch (...) {
      errlog("Unspecified error while processing query received over DoH");
    }
  }
}
#endif /* USE_SINGLE_ACCEPTOR_THREAD */

/* Called in the main DoH thread if h2o finds that dnsdist gave us an answer by writing into
   the dohresponsepair[0] side of the pipe so from:
   - handleDOHTimeout() when we did not get a response fast enough (called
     either from the health check thread (active) or from the frontend ones (reused))
   - dnsdistclient (error 500 because processDOHQuery() returned a negative value)
   - processDOHQuery (self-answered queries)
   */
static void on_dnsdist(h2o_socket_t *listener, const char *err)
{
  /* we want to read as many responses from the pipe as possible before
     giving up. Even if we are overloaded and fighting with the DoH connections
     for the CPU, the first thing we need to do is to send responses to free slots
     anyway, otherwise queries and responses are piling up in our pipes, consuming
     memory and likely coming up too late after the client has gone away */
  while (true) {
    DOHUnit *ptr = nullptr;
    DOHServerConfig* dsc = reinterpret_cast<DOHServerConfig*>(listener->data);
    ssize_t got = read(dsc->dohresponsepair[1], &ptr, sizeof(ptr));

    if (got < 0) {
      if (errno != EWOULDBLOCK && errno != EAGAIN) {
        errlog("Error reading a DOH internal response: %s", strerror(errno));
      }
      return;
    }
    else if (static_cast<size_t>(got) != sizeof(ptr)) {
      errlog("Error reading a DoH internal response, got %d bytes instead of the expected %d", got, sizeof(ptr));
      return;
    }

    DOHUnitUniquePtr du(ptr, DOHUnit::release);
    if (!du->req) { // it got killed in flight
      du->self = nullptr;
      continue;
    }

    if (!du->tcp &&
        du->truncated &&
        du->query.size() > du->proxyProtocolPayloadSize &&
        (du->query.size() - du->proxyProtocolPayloadSize) > sizeof(dnsheader)) {
      /* restoring the original ID */
      dnsheader* queryDH = reinterpret_cast<struct dnsheader*>(du->query.data() + du->proxyProtocolPayloadSize);
      queryDH->id = du->ids.origID;
      du->ids.forwardedOverUDP = false;
      du->tcp = true;
      du->truncated = false;
      du->response.clear();

      auto cpq = std::make_unique<DoHCrossProtocolQuery>(std::move(du), false);

      if (g_tcpclientthreads && g_tcpclientthreads->passCrossProtocolQueryToThread(std::move(cpq))) {
        continue;
      }
      else {
        vinfolog("Unable to pass DoH query to a TCP worker thread after getting a TC response over UDP");
        continue;
      }
    }

    if (du->self) {
      // we are back in the h2o main thread now, so we don't risk
      // a race (h2o killing the query) when accessing du->req anymore
      *du->self = nullptr; // so we don't clean up again in on_generator_dispose
      du->self = nullptr;
    }

    handleResponse(*dsc->df, du->req, du->status_code, du->response, dsc->df->d_customResponseHeaders, du->contentType, true);
  }
}

/* called when a TCP connection has been accepted, the TLS session has not been established */
static void on_accept(h2o_socket_t *listener, const char *err)
{
  DOHServerConfig* dsc = reinterpret_cast<DOHServerConfig*>(listener->data);
  h2o_socket_t *sock = nullptr;

  if (err != nullptr) {
    return;
  }

  if ((sock = h2o_evloop_socket_accept(listener)) == nullptr) {
    return;
  }

  const int descriptor = h2o_socket_get_fd(sock);
  if (descriptor == -1) {
    h2o_socket_close(sock);
    return;
  }

  ComboAddress remote;
  if (h2o_socket_getpeername(sock, reinterpret_cast<struct sockaddr*>(&remote)) == 0) {
    vinfolog("Dropping DoH connection because we could not retrieve the remote host");
    h2o_socket_close(sock);
    return;
  }

  if (!dnsdist::IncomingConcurrentTCPConnectionsManager::accountNewTCPConnection(remote)) {
    vinfolog("Dropping DoH connection from %s because we have too many from this client already", remote.toStringWithPort());
    h2o_socket_close(sock);
    return;
  }

  auto concurrentConnections = ++dsc->cs->tcpCurrentConnections;
  if (dsc->cs->d_tcpConcurrentConnectionsLimit > 0 && concurrentConnections > dsc->cs->d_tcpConcurrentConnectionsLimit) {
    --dsc->cs->tcpCurrentConnections;
    h2o_socket_close(sock);
    return;
  }

  if (concurrentConnections > dsc->cs->tcpMaxConcurrentConnections.load()) {
    dsc->cs->tcpMaxConcurrentConnections.store(concurrentConnections);
  }

  auto& conn = t_conns[descriptor];

  gettimeofday(&conn.d_connectionStartTime, nullptr);
  conn.d_nbQueries = 0;
  conn.d_acceptCtx = std::atomic_load_explicit(&dsc->accept_ctx, std::memory_order_acquire);
  conn.d_desc = descriptor;
  conn.d_remote = remote;

  sock->on_close.cb = on_socketclose;
  sock->on_close.data = &conn;
  sock->data = dsc;

  ++dsc->df->d_httpconnects;

  h2o_accept(conn.d_acceptCtx->get(), sock);
}

static int create_listener(std::shared_ptr<DOHServerConfig>& dsc, int fd)
{
  auto sock = h2o_evloop_socket_create(dsc->h2o_ctx.loop, fd, H2O_SOCKET_FLAG_DONT_READ);
  sock->data = dsc.get();
  h2o_socket_read_start(sock, on_accept);

  return 0;
}

#ifndef DISABLE_OCSP_STAPLING
static int ocsp_stapling_callback(SSL* ssl, void* arg)
{
  if (ssl == nullptr || arg == nullptr) {
    return SSL_TLSEXT_ERR_NOACK;
  }
  const auto ocspMap = reinterpret_cast<std::map<int, std::string>*>(arg);
  return libssl_ocsp_stapling_callback(ssl, *ocspMap);
}
#endif /* DISABLE_OCSP_STAPLING */

#if OPENSSL_VERSION_MAJOR >= 3
static int ticket_key_callback(SSL *s, unsigned char keyName[TLS_TICKETS_KEY_NAME_SIZE], unsigned char *iv, EVP_CIPHER_CTX *ectx, EVP_MAC_CTX *hctx, int enc)
#else
static int ticket_key_callback(SSL *s, unsigned char keyName[TLS_TICKETS_KEY_NAME_SIZE], unsigned char *iv, EVP_CIPHER_CTX *ectx, HMAC_CTX *hctx, int enc)
#endif
{
  DOHAcceptContext* ctx = reinterpret_cast<DOHAcceptContext*>(libssl_get_ticket_key_callback_data(s));
  if (ctx == nullptr || !ctx->d_ticketKeys) {
    return -1;
  }

  ctx->handleTicketsKeyRotation();

  auto ret = libssl_ticket_key_callback(s, *ctx->d_ticketKeys, keyName, iv, ectx, hctx, enc);
  if (enc == 0) {
    if (ret == 0) {
      ++ctx->d_cs->tlsUnknownTicketKey;
    }
    else if (ret == 2) {
      ++ctx->d_cs->tlsInactiveTicketKey;
    }
  }

  return ret;
}

static void setupTLSContext(DOHAcceptContext& acceptCtx,
                            TLSConfig& tlsConfig,
                            TLSErrorCounters& counters)
{
  if (tlsConfig.d_ciphers.empty()) {
    tlsConfig.d_ciphers = DOH_DEFAULT_CIPHERS;
  }

  auto [ctx, warnings] = libssl_init_server_context(tlsConfig, acceptCtx.d_ocspResponses);
  for (const auto& warning : warnings) {
    warnlog("%s", warning);
  }

  if (tlsConfig.d_enableTickets && tlsConfig.d_numberOfTicketsKeys > 0) {
    acceptCtx.d_ticketKeys = std::make_unique<OpenSSLTLSTicketKeysRing>(tlsConfig.d_numberOfTicketsKeys);
#if OPENSSL_VERSION_MAJOR >= 3
    SSL_CTX_set_tlsext_ticket_key_evp_cb(ctx.get(), &ticket_key_callback);
#else
    SSL_CTX_set_tlsext_ticket_key_cb(ctx.get(), &ticket_key_callback);
#endif
    libssl_set_ticket_key_callback_data(ctx.get(), &acceptCtx);
  }

#ifndef DISABLE_OCSP_STAPLING
  if (!acceptCtx.d_ocspResponses.empty()) {
    SSL_CTX_set_tlsext_status_cb(ctx.get(), &ocsp_stapling_callback);
    SSL_CTX_set_tlsext_status_arg(ctx.get(), &acceptCtx.d_ocspResponses);
  }
#endif /* DISABLE_OCSP_STAPLING */

  libssl_set_error_counters_callback(ctx, &counters);

  if (!tlsConfig.d_keyLogFile.empty()) {
    acceptCtx.d_keyLogFile = libssl_set_key_log_file(ctx, tlsConfig.d_keyLogFile);
  }

  h2o_ssl_register_alpn_protocols(ctx.get(), h2o_http2_alpn_protocols);

  acceptCtx.d_ticketsKeyRotationDelay = tlsConfig.d_ticketsKeyRotationDelay;
  if (tlsConfig.d_ticketKeyFile.empty()) {
    acceptCtx.handleTicketsKeyRotation();
  }
  else {
    acceptCtx.loadTicketsKeys(tlsConfig.d_ticketKeyFile);
  }

  auto nativeCtx = acceptCtx.get();
  nativeCtx->ssl_ctx = ctx.release();
}

static void setupAcceptContext(DOHAcceptContext& ctx, DOHServerConfig& dsc, bool setupTLS)
{
  auto nativeCtx = ctx.get();
  nativeCtx->ctx = &dsc.h2o_ctx;
  nativeCtx->hosts = dsc.h2o_config.hosts;
  ctx.d_ticketsKeyRotationDelay = dsc.df->d_tlsConfig.d_ticketsKeyRotationDelay;

  if (setupTLS && dsc.df->isHTTPS()) {
    try {
      setupTLSContext(ctx,
                      dsc.df->d_tlsConfig,
                      dsc.df->d_tlsCounters);
    }
    catch (const std::runtime_error& e) {
      throw std::runtime_error("Error setting up TLS context for DoH listener on '" + dsc.df->d_local.toStringWithPort() + "': " + e.what());
    }
  }
  ctx.d_cs = dsc.cs;
}

void DOHFrontend::rotateTicketsKey(time_t now)
{
  if (d_dsc && d_dsc->accept_ctx) {
    d_dsc->accept_ctx->rotateTicketsKey(now);
  }
}

void DOHFrontend::loadTicketsKeys(const std::string& keyFile)
{
  if (d_dsc && d_dsc->accept_ctx) {
    d_dsc->accept_ctx->loadTicketsKeys(keyFile);
  }
}

void DOHFrontend::handleTicketsKeyRotation()
{
  if (d_dsc && d_dsc->accept_ctx) {
    d_dsc->accept_ctx->handleTicketsKeyRotation();
  }
}

time_t DOHFrontend::getNextTicketsKeyRotation() const
{
  if (d_dsc && d_dsc->accept_ctx) {
    return d_dsc->accept_ctx->getNextTicketsKeyRotation();
  }
  return 0;
}

size_t DOHFrontend::getTicketsKeysCount() const
{
  size_t res = 0;
  if (d_dsc && d_dsc->accept_ctx) {
    res = d_dsc->accept_ctx->getTicketsKeysCount();
  }
  return res;
}

void DOHFrontend::reloadCertificates()
{
  auto newAcceptContext = std::make_shared<DOHAcceptContext>();
  setupAcceptContext(*newAcceptContext, *d_dsc, true);
  std::atomic_store_explicit(&d_dsc->accept_ctx, newAcceptContext, std::memory_order_release);
}

void DOHFrontend::setup()
{
  registerOpenSSLUser();

  d_dsc = std::make_shared<DOHServerConfig>(d_idleTimeout, d_internalPipeBufferSize);

  if  (isHTTPS()) {
    try {
      setupTLSContext(*d_dsc->accept_ctx,
                      d_tlsConfig,
                      d_tlsCounters);
    }
    catch (const std::runtime_error& e) {
      throw std::runtime_error("Error setting up TLS context for DoH listener on '" + d_local.toStringWithPort() + "': " + e.what());
    }
  }
}

static h2o_pathconf_t *register_handler(h2o_hostconf_t *hostconf, const char *path, int (*on_req)(h2o_handler_t *, h2o_req_t *))
{
  h2o_pathconf_t *pathconf = h2o_config_register_path(hostconf, path, 0);
  if (pathconf == nullptr) {
    return pathconf;
  }
  h2o_filter_t *filter = h2o_create_filter(pathconf, sizeof(*filter));
  if (filter) {
    filter->on_setup_ostream = on_response_ready_cb;
  }

  h2o_handler_t *handler = h2o_create_handler(pathconf, sizeof(*handler));
  if (handler != nullptr) {
    handler->on_req = on_req;
  }

  return pathconf;
}

// this is the entrypoint from dnsdist.cc
void dohThread(ClientState* cs)
{
  try {
    std::shared_ptr<DOHFrontend>& df = cs->dohFrontend;
    auto& dsc = df->d_dsc;
    dsc->cs = cs;
    dsc->df = cs->dohFrontend;
    dsc->h2o_config.server_name = h2o_iovec_init(df->d_serverTokens.c_str(), df->d_serverTokens.size());

#ifndef USE_SINGLE_ACCEPTOR_THREAD
    std::thread dnsdistThread(dnsdistclient, dsc->dohquerypair[1]);
    dnsdistThread.detach(); // gets us better error reporting
#endif

    setThreadName("dnsdist/doh");
    // I wonder if this registers an IP address.. I think it does
    // this may mean we need to actually register a site "name" here and not the IP address
    h2o_hostconf_t *hostconf = h2o_config_register_host(&dsc->h2o_config, h2o_iovec_init(df->d_local.toString().c_str(), df->d_local.toString().size()), 65535);

    for(const auto& url : df->d_urls) {
      register_handler(hostconf, url.c_str(), doh_handler);
      dsc->paths.insert(url);
    }

    h2o_context_init(&dsc->h2o_ctx, h2o_evloop_create(), &dsc->h2o_config);

    // in this complicated way we insert the DOHServerConfig pointer in there
    h2o_vector_reserve(nullptr, &dsc->h2o_ctx.storage, 1);
    dsc->h2o_ctx.storage.entries[0].data = dsc.get();
    ++dsc->h2o_ctx.storage.size;

    auto sock = h2o_evloop_socket_create(dsc->h2o_ctx.loop, dsc->dohresponsepair[1], H2O_SOCKET_FLAG_DONT_READ);
    sock->data = dsc.get();

    // this listens to responses from dnsdist to turn into http responses
    h2o_socket_read_start(sock, on_dnsdist);

    setupAcceptContext(*dsc->accept_ctx, *dsc, false);

    if (create_listener(dsc, cs->tcpFD) != 0) {
      throw std::runtime_error("DOH server failed to listen on " + df->d_local.toStringWithPort() + ": " + strerror(errno));
    }
    for (const auto& [addr, fd] : cs->d_additionalAddresses) {
      if (create_listener(dsc, fd) != 0) {
        throw std::runtime_error("DOH server failed to listen on additional address " + addr.toStringWithPort() + " for DOH local" + df->d_local.toStringWithPort() + ": " + strerror(errno));
      }
    }

    bool stop = false;
    do {
      int result = h2o_evloop_run(dsc->h2o_ctx.loop, INT32_MAX);
      if (result == -1) {
        if (errno != EINTR) {
          errlog("Error in the DoH event loop: %s", strerror(errno));
          stop = true;
        }
      }
    }
    while (stop == false);

  }
  catch (const std::exception& e) {
    throw runtime_error("DOH thread failed to launch: " + std::string(e.what()));
  }
  catch (...) {
    throw runtime_error("DOH thread failed to launch");
  }
}

void handleUDPResponseForDoH(DOHUnitUniquePtr&& du, PacketBuffer&& udpResponse, InternalQueryState&& state)
{
  du->response = std::move(udpResponse);
  du->ids = std::move(state);

  const dnsheader* dh = reinterpret_cast<const struct dnsheader*>(du->response.data());
  if (!dh->tc) {
    static thread_local LocalStateHolder<vector<DNSDistResponseRuleAction>> localRespRuleActions = g_respruleactions.getLocal();
    static thread_local LocalStateHolder<vector<DNSDistResponseRuleAction>> localCacheInsertedRespRuleActions = g_cacheInsertedRespRuleActions.getLocal();

    DNSResponse dr(du->ids, du->response, du->downstream);
    dnsheader cleartextDH;
    memcpy(&cleartextDH, dr.getHeader(), sizeof(cleartextDH));

    dr.ids.du = std::move(du);
    if (!processResponse(dr.ids.du->response, *localRespRuleActions, *localCacheInsertedRespRuleActions, dr, false)) {
      if (dr.ids.du) {
        dr.ids.du->status_code = 503;
        sendDoHUnitToTheMainThread(std::move(dr.ids.du), "Response dropped by rules");
      }
      return;
    }

    if (dr.isAsynchronous()) {
      return;
    }

    du = std::move(dr.ids.du);
    double udiff = du->ids.queryRealTime.udiff();
    vinfolog("Got answer from %s, relayed to %s (https), took %f usec", du->downstream->d_config.remote.toStringWithPort(), du->ids.origRemote.toStringWithPort(), udiff);

    handleResponseSent(du->ids, udiff, dr.ids.origRemote, du->downstream->d_config.remote, du->response.size(), cleartextDH, du->downstream->getProtocol(), true);

    ++g_stats.responses;
    if (du->ids.cs) {
      ++du->ids.cs->responses;
    }
  }
  else {
    du->truncated = true;
  }

  sendDoHUnitToTheMainThread(std::move(du), "DoH response");
}

#else /* HAVE_DNS_OVER_HTTPS */

void handleDOHTimeout(DOHUnitUniquePtr&& oldDU)
{
}

#endif /* HAVE_DNS_OVER_HTTPS */